The study of the influence of different shear stress on the mRNA expression of scavenger receptor class B type 1 in endothelial cells / 生物医学工程学杂志

The present paper is to research the expression level of the mRNA of scavenger receptor class B type 1-receptor of high-density lipoprotein in endothelial cells after being treated by different shear stress. The second to fourth generations of the cultured human umbilical vein endothelial cells (HUVECs) were used in the experiment. The cells were divided into two groups. The first group was the control group which was not dealt with shear stress; the second group was the experimental group which concluded low shear stress group (4.2 dyne/cm2), moderate shear stress group (8.4 dyne/cm2) and high shear stress group (15 dyne/cm2). The load time was 1h, 2h, 4h and 8h, respectively. Harvesting the cells and extracting total RNA after being treated by different shear stresses, the expression level of the SR-B1 mRNA was detected by semi-quantitative RT-PCR technic. It was found that the expression of SR-B1 mRNA became weaker and weaker compared to the control group when it was stimulated continuously by the low shear stress, the lowest expression of SR-B1 mRNA appeared at 8h. In the moderate shear stress group, the expression of SR-B1 mRNA increased obviously. Compared to the control group, there was significant difference after being treated with 2h. In the high shear stress group, the expression of SR-B1 mRNA increased immediately when it was stimulated by the shear stress. And the expression of SR-B1 mRNA arrived peak value at 4h. Compared to the control group, there was significant difference after being treated for 1h. It was concluded that the harmful mechanism of the low shear stress is that it can increase the incidence of the atherosclerosis by reducing the reverse cholesterol transport and endothelial protection through decreasing the expression of the SR-B1. Otherwise, the high shear stress prevent the genesis of atherosclerosis by the contrary mechanism.

Comparison of adhesion of different endothelial cells under shear stress load in the flow field in vitro / 生物医学工程学杂志

This study was aimed to compare the differences of adhesion properties of endothelial cells (EC) from arteries (AEC), veins (VEC) and capillaries (MVEC) under shear stress condition, and to explore whether they can get the same adhesive ability as graft in similar shear stress conditions. With mended parallel plate flow apparatus and peristalsis pump providing fluid shear stress used, endothelial culture models were established in vitro with the same environmental factors as steady culture. To compare the adhesion among three kinds of endothelial cells under dynamic condition and static condition, the dynamic change of cytoskeletal actin filaments and the effects of different adhesive proteins coated on the adhesion of EC to the glass were studied. The cultured endothelial cells under flow conditions were extended and arranged along the direction of flow. The adhesive ability from high to low under static condition were AEC, MVEC and VEC (VEC compared with AEC or MVEC, P < 0.05), sequentially. The adhesion of endothelial cells from variety sources under dynamic culture condition was significantly increased than that of the static groups. The ratio of cell retention was not significantly different between AEC and MVEC. But VEC was significantly different (P < 0.05) compared with AEC or MVEC. The actin filaments (F-actin) were bundled together and arranged along the direction of flow after fluid culture. Dense peripheral band (DPB) gradually disappeared and distinct stress fibers were formed, which even interconnected to form a whole in the MVEC. The adhesion of AEC, VEC and MVEC under shear stress conditions are more significantly increased than those under the static culture conditions, and the MVEC can achieve the same adhesion as AEC.

Low-intensity anticoagulation therapy in the pregnant women with mechanical heart valves:a report with 56 cases / 中华胸心血管外科杂志

Objective To evaluate the method of low-intensity anticoagulation therapy in the pregnant women who had received mechanical heart valve replacemant, and the effects of warfarin on the pregnant women and their fetus. Methods This retrospective study involved 56 pregnant women( 61 pregnancies)who had received mechanical heart valve replacement.Their pregnant status, delivery, and anticoagulation therapy were observed and followed-up between May 1986 and November 2009 at West China Hospital of Sichuan University. Results All patients took oral anticoagulant (warfarin) throughout pregnancy. The dose of domestic warfarin was ( 3.02 ± 0.85 ) mg/d ( in 42 cases), and the dose of imported warfarin was (2.84 ± 0.57 )mg/d (in 14 cases). The mean INR value of 401 samples from patients was 1.67 ±0.58. No thromboembolism or major hemorrhagic complications occurred. Minor bleeding occurred in 11 pregnancies. Forty-seven patients had term delivery, 7 had premature birth, 6 had spontaneous abortion, and 1 had intrauterine fetal death. Six newborns were born with low birth weight (2.3 ± 0. 5 ) kg, and no abnormal fetus was observed. Conclusion The low-intensity anticoagulation therapy with warfarin (at a dose of less than 5 mg/d) and a INR target of 1.5 to 2.0 was safe and convenient for the pregnant women,who had received mechanical heart valve replacement. The abnormalities rate of fetus was low.

Pressure change-mediated effects on vasoactive protein of endothelial cells in the flow field in vitro / 生物医学工程学杂志

Lining the inner surface of the walls of blood vessels, Endothelial cells (ECs) go beyond providing selective membrane to maintain the natural structure and function of vessels; they also synthesize varieties of vasoactive proteins to modify the pressure shift in the local flow field and hence they adapt the physiological activities of vessels. In this experiment, ELISA and RT-PCR technologies were adopted. We set up five different pressure loaded ECs groups,one non-activated cultured ECs group and one single shear stress loaded ECs group. Such a design was intended to demonstrate the effects of pressure shift on the expression of vasoactive protein synthesized by ECs [Endothelin-1(ET-1), endothelial Nitric Oxide Synthase (eNOS), Cyclooxygenase-2(COX-2) and Vascular Endothelial Growth Factor(VEGF)]. Our aim was to elucidate the mechanism of the pressure shift mediated dysfunction in ECs and the related dose-effect relationship. Based on these data, we suggest that ECs could modify the expression of vasoactive protein for adapting to the pressure shift in the local flow field; while in the process of--40 cmH2O induced ECs' dysfunction, the vasoactive proteins eNOS, COX-2 and VEGF play an important role in protecting ECs.

Pressure mediated effects on proliferation, apoptosis and apoptosis-associated protein of endothelial cells in the flow field in vitro / 生物医学工程学杂志

The changes of pressure in local circulation flow field and the alterations of biorheological characteristics in Endothelial cells (ECs) would follow the geometric changes of cardiovascular wall structures and would further result in distinct pathophysiological changes of endothelial cellular proliferation and vitality. This experiment is designed to observe the effects of pressure shift on ECs proliferation, apoptosis, and expression of apoptosis-associated protein, to elucidate the influences of pressure shift on the vitality of ECs, and to shed light on the dose-effect relationship concerned. By adopting flow cytometery, transmission electron microscopy, real-time RT-PCR and Western blotting, we set the levels of pressure loading ECs groups and set down the non-activated cultured ECs,single shear stress loading ECs as the control group for studies on the ultra-structure alterations, on the distribution of cell cycle and the changes of proliferation and apoptosis in ECs. We also investigated the changes of the expression of Caspase-3 gene and the changing regularity of P53, Bcl-2 and Fas protein at the translation level. When ECs being exposed to decreased pressure shift (-40 cmH2O), distinct apoptosis in ECs could be observed and a pattern of duration-dependence was seen. The expressions of P53, Bcl-2 and Fas proteins are essential for regulating the genesis and process of ECs apoptosis induced by -40 cmH2O pressure.

Mechanisms of insulin resistance during ischemia reperfusion in the cardiomyocytes of rat / 中华胸心血管外科杂志

Objective Recent.studies have found a strong association of insulin resistance, which might occur during ischemia reperfusion in vitro in the experimental dogs, with disturbed function of cardiomyocytes. Obvious acute insulin resistance, along with glucose dysmetabolism in the reperfused cardiomyocytes, was furher observed in the study performed with ischemia-reperfused ventric- ular myocytes of rats. We tried to investigate preliminarily the molecular mechanisms of insulin resistance in the cardiomyocytes after ischemia reperfusion. Methods An experimental model of insulin-stimulated ischemia reperfusion (SI/R) was created by isolating cardiomyocytes from adult rats. Glucose uptake of the cardiomyoctyes was evaluated with isotope-labeling technique. Glucose trans- porter 4 (GLUT4) translocation induced by insulin was investigated with Western blot analysis, and the intracellular level of free Ca2+ ([Ca2+]I) was measured quantitatively with Ca2+ indicator Fura-2. Results Insulin can stimulated glucose uptake by cardiomyo- cytes, indicating that these cells were insulin-sensitive. Cardiomyocytes were demonstrated notable acute insulin resistmce during reperfusion. Insulin-stimulated GLUT4 translocation in the cardiomyocytes 15 minutes after reperfusion was 72.2% of that in the con- trol group(P<0.05), in which the GLUT4 content in plasma membrane remained unchanged. The finding suggested that a disturbed GLUT4 translocation might happen in the cardiomyocytes during insulin-stimulated ischemia-reperfusion. Calcium overload was identi- fied in the cardiomyocytes with ischemia reperfusion. At 15 minutes of reperfusion, [Ca2+]I was significantly higher in the reperfused cardiomyocytes than that in the control cardiomyocytes[(318.66±23.06)vs(130.70±0.82) nmol/L, P<0.05], and kept at a higher level [(177.79±17.46) nmol/L] at 60 minutes of reperfusion (P<0.05, vs control). Partial correlation analysis revealed a negative correlation of[Ca2+]I with insulin-induced ghcose uptake in the cardiomyoctyes (r = -0.557,P=0.006). Conclusion Disturbed GLUT4 translocation and decreased intrinsic activity may be important molecular mechanisms for the development of insulin resistance in the cardiomyocytes of rat during insulin-simulated ischemia reperfusion,. [Ca2+]I overload may account for the de- creased intrinsic activity d GLUT4.

Modification of the method for establishing myocardial infarction model in rats / 生物医学工程学杂志

This study was conducted to modify the method for establishing the model of myocardial infarction by ligation of the left anterior descending branch (LAD) of coronary artery in rats, and then observations on them were made with the use of electrocardiography, heart function exam and histomorphology. 30 adult male inbred strain Wistar rats were randomly divided into two groups: sham group (n = 5) and model group (n = 25). Each rat in the model group underwent a ligation of the left anterior descending branch. Subsequently, the two groups were compared by use of electrocardiography, heart function and histomorphology. The results have demonstrated that, after being improved, the ligation of the left anterior descending branch of coronary artery is a good method to establish the stable model of myocardial infarction. It can be applied to the research in mechanism and treatment of myocardial infarction.

Clinical study of perventricular device closure of non-muscular ventricular septal defects in 39 infants / 中华胸心血管外科杂志

Objiective To evaluate the effect of pearventricular device closure of non-muscular ventricular defercts(VSDs) in infants.Methods From April 2007 to February 2008,39 patients with non-muscular VSDs were received off pump surgical treatment,perventricular device closure were for all the patients.There were 16 males and 23 females with mean age of(14.5±7.8) months(12 to 36 months and mean weight of(12.4±2.3)kg(8.5 to 18.0 kg).There were 34 perimembranous and 5 subateria VSD.The diameter of defects were 3.0 to 11 mm[mean(6.1±2.0)mm].Results Thirty-seven(94.9%)VSDs ere successfully closed,while two were repaired under cardiopulmonary bypass(CPB)instead of device closure because of the complication of moderat aortic reurgitation.The diameter of occluders were 4 to 12mm[mean(8.2±2.0)mm].The tricuspid regurgitations decareasded after operation in 3 patients with perimenmbranous VSDs,while the closure caused new mild or trace tricuspid regurgitations in 8 patients.Six patients with perimembranours VSDs acquired the incomplete right bundle branch blocks affter device closure.The length of hospital stay was 3 to 5 days[mean(3.4±0.4)]after operation and no petient had blood transfusion.Conclustion Perventricular device closure is probably an effective and safe treatment for non-muscular VSDs in unfants.

Changes of the metabolism of anti-oxidation competence of endothelial cells induced from mesenchymal stem cells after fluid shear stress loading / 生物医学工程学杂志

This study examined the effects of flow shear stress on the bio-capacity of the endothelial cells' induced from mesenchymal stem cells (MSCs). After cultivating the SD rat mesenchymal stem cells in vitro, we exposed them under different intensity of flow shear stress and induced these cells to endothelial cells. The variations of total anti-oxidation competence (T-AOC) and quantity of nitrogen monoxide (NO) were tested. The results showed that shear stress has an enhanced effect on the T-AOC and NO of endothelial cells induced from MSCs in an intensity-dependent manner. Flow shear stress could provide a protective action on the in vitro induction of endothelial cells, thus formulating a theoretical foundation for the therapeutics of ischemic heart diseases and vascular tissue engineering.

Pressure shift mediated changes of vascular endothelial cell morphology and adhesive function in the flow field in vitro / 生物医学工程学杂志

In mankind, the circulation system is a closed pressure-loaded system; the pressure in circulation flow field would change with the variation of natural or pathological geometry of the local bloodvessel, and the pressure shift induced by the variation of vascular geometry would lead to a series of physiological and pathological changes in the endothelial cells (ECs). This experiment is designed to elucidate the effects of different pressure shift on F-actin alignment and expression in cultured endothelial cells in vitro, and to investigate the relationship between the altered pressure shift and the expression intensity of Vascular adhesion molecule (VCAM) and Integrin alphaVbeta3. Non-activated cultured ECs and single shear stress loaded ECs as control group were set, the double-immuno-fluoro-cytochemistry, laser confocal scanning microscopy and image analysis system were used to observe the expression of VCAM, Integrin alphaVbeta3 and F-actin in endothelial cells which were exposed to levels of pressure shift in an improved parallel plate flow chamber. When exposed to different decreased pressure shift, the expression intensity of VCAM, Integrin alphaVbeta3 and F-actin showed regular changes. The decreased pressure shift resulted in changes in cell alignment and cytoskeleton F-actin, and also affected ECs adhesion function and transmembrane mechanotransduction function which were represented by VCAM and Integrin alphaVbeta3 respectively.

Particle image velocimetry in measuring the flow fields distribution in carotid artery bifurcation model / 生物医学工程学杂志

To understand the local hemodynamics of modified TF-AHCB carotid bifurcation model, using particle image velocimetry technique to measure the instantaneous velocity distribution of the model attatched to a circuit. The velocity was controlled by regulating the height of the reservoir. The working fluid consists of glycerine and water mixture with viscosity of 3.75 mPa.s similar to human blood. Instantaneous velocity fields were obtained by PIV and the shear stresses were calculated according to the velocity. The results showed that inside the model, there were a large flow separation and an anticlockwise rotating vortex on the lateral wall of ICA, The location and distance of the vortex changed with the flow velocity. The higher the flow velocity, the smaller the vortex distance, and the farther the location. The shear stresses on the lateral wall were significantly lower in all work condition. And there a low shear stress kernel when the velocity was lower than 0.839 m/s. The location of the low shear stress was just the position of atherosclerosis. The flow pattern inside the model consists of large flow separation and vortex zones. And there are low shear stress zones at the lateral wall of ICA, Where are thought to be associated with the genesis of atherosclerosis.

A preliminary study on the extraction method of velocity pulsated signals in the velocity spectrum image of pulsed Doppler ultrasounds in vitro / 生物医学工程学杂志

Focus on the defects of the extraction method of velocity pulsated signals in the velocity spectrum image of pulsed Doppler ultrasounds (such as the limited data, great amount of work and low reproducibility), we combine the earlier research results and the basic rules of the velocity spectrum image, and employing the visual basics plateau, to design and develop a software to extract the velocity signals from the spectrum image automatically. Compare the mean velocity and RNS between the PIV and the PDU resulting from the method, the correlations are r = 0.93 and r = 0.78 respectively. The study reveals the software increase the amount of valid data, decrease the amount of work and increase reproducibility of the signals extraction. The method may be an effective way to analyse the velocity spectrum image of PDU in clinic.

Design and adjustment of a hydrodynamic model of turbulent flow separation area for in vitro experiment on the downstream of tubal stenosis / 生物医学工程学杂志

This paper reports the establishment of a model of turbulent flow separation area for experiment on the downstream of tubal stenosis, and adjust it to cooperate with the velocity and turbulent shear stress (TSS) detection by means of the particle image velocimetry (PIV), and with the pressure detection of pressure sensor in vitro. The velocity, TSS and wall pressure characteristics of the downstream of tubal stenosis were quantitatively detected and analyzed via the PIV and pressure sensor. And the hydrodynamic characteristics of the velocity, TSS and wall pressure in the flow separation area were primarily understood. The model can cooperate smoothly with the PIV and pressure sensor to detect the velocity, TSS and wall pressure; there exist low velocity, low TSS and low pressure in the flow separation area downstream of tubal stenosis.

Effect of RGD peptide on adhesive stability of human umbilical vein endothelial cell on polyethylene terephthalate surface / 生物医学工程学杂志

In this study for exploring the effect of RGD peptide on adhesive stability of endothelial cells biomaterial surface, all materials were divided into three groups, RGD group (PET covalently grafted synthetic RGD peptides), control group (PET precoated with fibronectin) and blank group (Non-coated surface). Cultured human umbilical vein endothelial cells (HUVECs) were seeded on the materials, then adhesive stability of HUVECs on the varied PET surfaces was observed under steady flow condition, and effects of shear stress and shear time on adherent cells were compared. The results showed that the resistance adherent endothelial cells to detachment by flow was shear stress and shear time dependent. Comparison three groups under the same condition revealed that the ECs retention rates of RGD-grafted or fibronectin-coated group were much higher than that of the non-coated group. Under 8.19 dyne/cm2 shear stress after 4h, retention rates were 13.73% (blank group), 43.33% (RGD group) and 40.75% (control group) respectively. These data indicated that RGD peptide can improve the adhesive stability of endothelial cell on biomaterial and the effect of RGD in vivo needs further studies.

Method for measuring different phases of left ventricular systole period with ultrasonic Doppler and synchronism electrocardiogram in normal persons / 生物医学工程学杂志

This study of methodology was aimed to assess the feasibility of measuring different phase of left ventricular systole period with ultrasonic Doppler and synchronism electrocardiogram. We measured the phases of left ventricular systole period and left ventricular volumes in 13 normal persons, using spectrum of aortic valve orifice flow and synchronism electrocardiogram. The values measured by routine method and by Doppler method were compared. The correlation and agreement between the measures ascertained by the two ways were analyzed. The time parameters of end systole of left ventricule showed no significant difference between the two ways (P>0.05); there was high linear correlation between the two parameters (r=0.91, P<0.01); there were good agreements between the two parameters of the two ways by Bland-Altman analysis. The volume parameters of left ventricular systole end showed no significant difference between the two ways (P>0.05); there was high linear correlation between the two parameters (r=0.97, P<0.01); there were good agreements between the two volume parameters of the two ways. The volume in the left ventricular systole end determined by Doppler method and the volume in the left ventricular diastole end determined by the routine method showed no significant difference (P>0.05); there was high linear correlation between the two parameters (r=0.98, P<0.01); there was good agreement between the two volume parameters of the two ways. It is feasible to measure different phases of left ventricular systole period with the combined use of ultrasonic Doppler and synchronism electrocardiogram, and this combinaterial method and the routine method can be replaced with each other according to the clinical setting.

Surgical treatment of lung cancer by video-assisted thoracoscopic surgery / 中国肺癌杂志

<p><b>BACKGROUND</b>To investigate the role of curative and palliative surgical treatment of lung cancer with video-assisted thoracoscopic surgery (VATS).</p><p><b>METHODS</b>Forty-three patients with lung cancer were prescribed operations with VATS, which included 5 cases of stage IA, 14 cases of IB, 1 case of IIA, 4 cases of IIB, 7 cases of IIIA, 6 cases of T4-IIIB and 6 cases of IV. The 7 patients of stage IIIA were previously staged as N0 before operation, but reevaluated as N2-IIIA after operation. There were 3 cases of malignant pleural effusion and 3 cases of pleural implantation in stage IIIB cases. There were 2 cases of cardiac tamponade, 1 case of solitary brain metastasis, and 3 cases of ipsilateral or contralateral solitary lung metastasis in cases of stage IV. The main methods of operation performed included lobectomy in 36 cases, wedge resection in 5 cases, and pericardial opening in 2 cases. Systemly mediastinal lymph node dissections were performed in 36 cases. Concurrent contralateral pulmonary wedge resections were performed in 2 cases of contralateral solitary lung metastasis. Malignant pleural effusions were prescribed resection of implantation nodules, electrocautery and pleurodesis.</p><p><b>RESULTS</b>There was no perioperative death or bronchial leak. Five cases suffered lung infection, and 2 cases occurred with incision infection. Malignant pleural effusion in the 3 cases was controlled satisfactorily. Two cases of pericardial opening died in 4 months and 8 months after operation respectively. The other patients were alive till present. Postoperative hospital stay was 5-15 days with average of 7.4 days, except of two cases of pericardial opening.</p><p><b>CONCLUSIONS</b>VATS is an alternative way for complete resection of early stage lung cancer. It is technically feasible to dissect mediastinal lymph node for accidental N2 lung cancer. VATS has significant advantage in concurrent bilateral pulmonary resection. The palliative operation of malignant pleural effusion and cardiac tamponade by VATS can markedly improve the quality of life of patients.</p>

PDTC reduces E-selectin expression on hypoxia/reoxygenation-stimulated endothelial cells / 中华胸心血管外科杂志

Objective: To study the mechanisms and treatment of ischemia/reperfusion injury. Expression of E selectin was measured and the effect on suppression of E selectin by the Pyrrolidine Dithiocarbamate was investigated. Methods: Endothelial cells were exposed to hypoxia, then returned to reoxygenation condition. ELISA methods were used to detect expression of E selectin. Results: E selectin expression on hypoxia/reoxygenation stimulated endothelial cells increased, PDTC could suppress translation of E selectin effectively. Conclusion: It seems that E selectin may act as a critical factor. PDTC may prove beneficial in the treatment of ischemia/reperfusion injury.

Effect of turbulent flow on adhesion molecules expression of vascular endothelial cells / 生物医学工程学杂志

Mechanical environment seems to be one of the most important surviving environment for vessel conduit and vascular endothelial cells(ECs), while adhesion is one of the most important physical characteristics of ECs. In this study, Flow chambers of steady laminar and turbulent flow are made and improved. Different flow-derived VCAM-1, ICAM-1 expressions are detected by laser confocal microscope. Spacial and temporal curves of the adhesion molecules are protracted. In laminar flow, expression of VCAM-1 is dramatically elevated, whereas the expression of ICAM-1 is transiently elevated and it immediately falls back to the baseline. In turbulent flow, expression of VCAM-1 declines, while expression of ICAM-1 slowly rises to a peak. These results indicate that such pathological flow field as turbulence exerts different influence on the adhesion of vascular ECs from laminar flow, and turbulence could be one of the most important reasons of the ECs structural and functional lesion.

Progress in studies of tissue-engineered heart valves / 生物医学工程学杂志

Valve replacement represents the most common surgical therapy for valvular heart diseases. However, the long-term results of the valve protheses in clinical use are not satisfying. Recently, with the development of tissue engineering, more and more studies are focusing on creating ideal valve substitutes through seeding autologous cells on biodegradable scaffold. This article describes the definition of valvular tissue engineering, the choice of scaffold biomaterials, the methods of cell culture and seeding, and the evaluation of tissue-engineered heart valves. Furthermore, the problems which should be resolved in the future are also presented in the article.

A methodological study of measuring quantitatively turbulent shear stree downstream of mitral stenosis in vivo using Doppler echocardiography / 生物医学工程学杂志

In order to establish a method for measuring quantitatively turbulent shear stress (TSS) downstream of mitral stenosis in vivo based on Doppler echocardiography and computer-aided image analysis, we used doppler echocardiography to record the spectrum of flow velocity downstream of mitral valve at several locations in normal persons and in patients with mitral stenosis. With the computer-aided analysis of spectrum images, the magnitude of TSS was measured at the locations. The results demonstrate that no matter how severe the mitral stenosis is, the TSS and relative turbulent intensity(Irel) at the central locations of jet are lower than those at the marginal ones. A significant difference in the quantitative items of TSS, Irel and flow field uniformity between normal persons and patients with varying-degree of mitral stenosis was noticed (P < 0.05). There was a significant correlation between these items and effective orifice area (EOA), and we found that the smaller EOA is, the more severe the extent of stenosis is and the greater the magnitude of both TSS and Irel are, and that the highest magnitude of TSS is focused on the marginal area of jet. These results indicate that there is an obvious correlation between TSS(measured by Doppler echocardiography combined with computer-aided image analysis) and flow field uniformity. They can coincidently reveal the hemodynamic changes resulting from mitral stenosis of varied severeness, implying that our method could exactly depict the magnitude of TSS downstream of mitral stenosis in vivo and is non-invasive and good for anti-disturbance. The method can be used to analyze quantitatively TSS in the flow field of heart valve in patients with valvular diseases.